裂叶红麻的光合器官数量性状与麻皮产量相关性分析

对６个裂叶红麻品种（系）不同光合器官的数量性状与干皮产量作了相关分析。结果表明总叶数、７裂叶数及麻皮长和麻皮宽的光合器官之间及与干皮产量之间的相关都是显著的，而圆叶数、３裂叶数及５裂叶数与干皮产量相关不显著。总对数、７裂叶数及麻皮长的数量性状其广义和狭义遗传力都很低．表明主要光合器官的表现易受环境影响，注意选择圆叶数性状可能有助于培育高产品种。     

Heritability estimates and response to selection for growth of Nile tilapia (Oreochromis niloticus) in low-input earthen ponds

This study presents results of two generations of selection (G₁ and G₂) for growth of Nile tilapia. The selection environment consisted of earthen ponds which were fertilized daily with 50 kg dry matter (dm)/ha chicken manure. No supplementary feeds were provided. In total, 6429 fully pedigreed experimental fish were included in the analysis. Survival till harvest was highly variable ranging from 35% to 77% and was affected by initial weight, pond, and age effects. Body weight at harvest (BW) increased from a mean of 67.4 g in the grandparental (unselected) population (G₀) to 129.5 g in G₂ was affected by initial weight, pond, sex and age effects. Generations were discrete and therefore genetic parameters were estimated separately for each year. Heritability estimates for BW ranged from 0.38 to 0.60, and the heritability for survival ranged from 0.03 to 0.14. The estimated selection response was 23.4 g (34.7%) between G₀ and G₁ and 13.0 g (14.9%) between G₁ and G₂. These results demonstrate the feasibility of selection for growth of Nile tilapia in low-input environments.     

Summer mortality of hatchery-produced Pacific oyster spat (Crassostrea gigas). I. Estimation of genetic parameters for survival and growth

The multidisciplinary project “MOREST” aims to improve our understanding of causes of summer mortality in Crassostrea gigas juveniles in France and to reduce its impact on oyster production. As part of the MOREST project, 43 full-sib families nested within 17 half-sib families were produced, planted out and tested in 3 sites during summer 2001 to assess to what extent genetic variability exists for this trait. A strong genetic basis was found for survival as narrow-sense heritability estimates ranged from 0.47 to 1.08, with higher values in sites where summer mortality was higher. Genetic correlations across sites were positive and very high for survival, indicating no genotype by environment interaction. In contrast, lower genetic variation was observed for growth in all sites. Finally, genetic correlations between growth and survival were low, in all sites. Selective breeding in a single site should therefore be an efficient means of improving survival in oysters less than one year old along the French Atlantic and Channel coastlines with only very limited effects on growth. As yield mostly depends on survival and growth, this approach should significantly improve harvestable yield. Possible reasons why a high genetic variance for survival appears to be maintained in wild populations are discussed.     

笃斯越橘生态耦合性分析与遗传效应评价

笃斯越橘（Vaccinium uliginosum Linn．）喜凉爽湿润的森林气候,集营养、药用、保健和商用价值于一体,为珍贵野生果类之一。采取固定标准地连续定位测定和临时标准地随机调查点面结合的方法,通过探讨高寒地区光、热、水、土资源与笃斯越橘生态耦合性,综合分析了数量性状的生态效应和亲本的遗传效应,为高寒地区的良种选育和引种驯化提供理论依据。结果表明：生境类型不同,数量性状存在一定的变异,以沼泽草句生境的变异最小,株高、果实纵和横径、单果质量及单株结实量的平均变异系数分别为4．31％、1．52％、1．11％、15．83％和3．45％;5个数量性状的遗传力较强,遗传增益中等,遗传力分别为0．995,0．982、0．990、0．997、0．995和1．000,遗传增益分别为8．40％、5．48％、5．53％、13．29％和4．63％,经济效益显著。     

抗虫棉品种(系)主要农艺性状配合力与遗传力分析

以12个抗虫棉品种(系)为亲本,采用6×6不完全双列杂交(NCⅡ),对所得F1代的8个农艺性状的配合力和遗传力进行分析。结果表明:单铃重与株高广义遗传力较高,其狭义遗传力也相对较高,可适当提早选择代数;而其余性状的广义遗传力高,狭力遗传力却较低,应适当延后选择代数;嘉星6号、中41和A48是综合性状良好的亲本;特殊配合力效应分析,较优组合为中41×A49、A1×A48、GK44×S08和嘉星6号×S08。     

春小麦高蛋白品系F93-486主要性状的遗传研究

以高蛋白品系Ｆ９３－４８６为母本，武春１号和陇春８号为父本组配了２个组合，在每个组合中获得Ｐ１、Ｐ２、Ｆ１、Ｆ２、Ｂ１和Ｂ２６个群体，并以此为供试材料对Ｆ９３－４８６的蛋白质含量，角质率等性状的遗传规律进行了研究。     

Genetic variation for dry matter and nitrogen accumulation and translocation in two-rowed spring barley: I. Dry matter translocation

A 4-year field study was carried out to determine dry matter and nitrogen accumulation until anthesis and at grain filling period and dry matter translocation and utilization in grain filling of barley. Twenty two-rowed spring barley (Hordeum vulgare ssp. distichum L.) cultivars originated from different countries (Yugoslavia, Germany, Australia, the Czeck Republic, Netherlands, France and USA) were grown during 1995–1998 on a non-calcareous chernozem soil near Novi Sad (45° 20′N, 15° 51′E, 86 m asl). Dry matter and nitrogen accumulation depended on the cultivar and year. In a year with favorable weather conditions, 58% of dry matter was accumulated during pre-anthesis, while in a year with less favorable weather the amount was 48%. In the favorable year 91% and in unfavorable year 65% of nitrogen was accumulated until anthesis. The results indicated that the greater amount of dry matter and nitrogen accumulated before anthesis. Dry matter translocation efficiency depended on the cultivar and ranged from 3 to 16.4%, while the contribution of pre-anthesis assimilates to kernel varied from 4 to 24.2%. Cultivars that have been developed for the growing conditions of the area where the experimental site was located, i.e. adapted ones, did not use pre-anthesis dry matter for grain filling. High positive correlations (P<0.01) were found between biomass at anthesis and biological yield, dry matter translocation efficiency, contribution of translocated dry matter to grain yield, and total plant nitrogen at maturity. Accumulated nitrogen at anthesis was positively correlated (P<0.01) with growing degree–days until anthesis, dry matter at anthesis and dry matter translocation parameters. Heritability for the investigated characters was rather high, over 0.60.     

Effects of high- vs. low-yield environments on selection for increased biomass yield in switchgrass

No information is available on the effects of different biomass yield environments on selection efficiency in switchgrass (Panicum virgatum L.) breeding improvement. This study was conducted to assess the effects of high- and low-biomass yield environments (HYE and LYE, respectively) on recurrent selection for general combining ability (RSGCA) in a lowland population of switchgrass (NL-94). The top 14 of 65 NL-94 C₀ parent plants were selected based on biomass yield of half-sib (HS) progeny tested for one post-establishment year under HYE and LYE conditions. Nine of the 14 C₀ parent plants were the same based on HS performance under HYE and LYE. Selected plants were intercrossed to produce NL-94 HYE and NL-94 LYE C₁ populations. One hundred and twenty-five HS C₁ progeny families (60 NL-94 HYE and 65 NL-94 LYE) were evaluated for biomass yield for 3 years (2002–2004) under HYE and LYE conditions. The HYE produced about 2.5 times higher biomass yields than the LYE in both C₀ and C₁ HS progeny tests. Estimated additive genetic variance and predicted gains from selection (ΔG) were high in the C₁ populations indicating that RSGCA should achieve higher biomass yields. Mean biomass yields of C₁ HS families originating from the LYE protocol were significantly higher than those of families originating from the HYE protocol in both HYE and LYE performance tests, suggesting greater selection response under LYE in the C₀ population. The estimates of narrow-sense heritability ( ) and ΔG from the C₁ populations indicate that positive response to selection for biomass yield is possible in subsequent cycles of selection under either HYE or LYE, with a possible small advantage for HYE.     

黄瓜早期若干数量性状遗传研究

利用4个黄瓜亲本，按4×4双列杂交法配制16个组合，测定早期产量、单瓜重、瓜条长度、瓜条直径、瓜把长度、果皮颜色6个数量性状。试验根据Hayman双列杂交法进行遗传分析。结果表明：单瓜重、瓜条长度、瓜条直径、瓜把长度、果皮颜色性状符合“加性-显性”效应模型，以加性效应为主，早期产量性状还受到上位性效应的作用，但以显性效应为主，存在超显性。除早期产量和瓜条直径外，其余各性状的广义遗传力和狭义遗传力都很高，表明受环境影响较小，可在早代进行选择；早期产量和瓜条直径的狭义遗传力较小，以非加性效应为主。     

小麦几种品质性状与产量性状早代选择效果的研究

以三个冬小麦单交组合为试验材料,采用遗传力、遗传进度和杂种后代品质性状表现在年份间的稳定性等分析方法,对小麦几种品质性状与产量性状早代选择的效果进行了研究.结果表明,沉淀值、容重的遗传力较高,蛋白质含量和单株蛋白质产量的遗传力较低.沉淀值、蛋白质产量在各杂种早代的相对预期遗传进度均在20%以上.不同的品质性状受环境的影响较大,但所表现出的稳定性不同.